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Ultra-stable CsMnX3 nanocrystals embedded glasses with bright and broad red photoluminescence (PL) emission at 649 nm were synthesized as an excellent red phosphor for white light-emitting diode (LED) devices with a high color rendering index (CRI).

Genetically engineered Escherichia coli biofilms can achieve the large-scale organization of protein-conjugated fluorescent RGB QDs into full-color Jabuticaba-like nanostructures with high complexity and specificity.

The 4.2 nm α-CsPbI3 quantum dots - polymer composite films with 630 nm emission and high stability have been achieved, which are used for LED displays with color gamut to 96% of the Rec. 2020 standard.

Manganese doped perovskite nanocrystals (NCs) have been synthesized by a novel two-step hot injection strategy with an unprecedented Mn doping efficiency of 48.5%, bright orange emission under ultraviolet light and X-ray excitation and a photoluminesce (PL) quantum yield of 84.4%, making them excellent luminescent materials.

A novel quaternary ammonium antinomy halide was synthesized and used to construct bright orange LEDs with a luminous efficiency of 24.5 lm W−1, which can run continuously in air for more than 1200 minutes without performance degradation.

In order to achieve high color rendering index (CRI) and low correlated color temperature (CCT) indoor lighting, single component phosphors with broadband dual emission emission are high demanded for white light emitting diodes (WLEDs). However, phosphors with such fluorescent properties are rare at present. Herein, we report a facile solid-state chemical method for the synthesis of single-component phosphor with broadband emission and large Stokes shift that can meet the requirements of future white light sources. These new tetrabutylammonium copper halides phosphors have excellent warm white emission characteristics, and their luminescence peaks located at 494 nm and 654 nm, respectively. The optimized photoluminescence (PL) quantum yield can reach 93.7%. The typical CIE coordinate of the as-fabricated WLED is at (0.3620, 0.3731) with CRI of 89 and low CCT of 4516 K.

All-inorganic nanocrystals (NCs) are of great importance in a range of electronic devices. However, current all-inorganic NCs suffer from limitations in their optical properties, such as low fluorescence efficiencies. Here, we develop a general surface treatment strategy to obtain intensely luminescent all-inorganic NCs (ILANs) by using designed metal salts with noncoordinating anions that play a dual role in the surface treatment process: (i) removing the original organic ligands and (ii) binding to unpassivated Lewis basic sites to preserve the photoluminescent (PL) properties of the NCs. The absolute photoluminescence quantum yields (PLQYs) of red-emitting CdSe/ZnS NCs, green-emitting CdSe/CdZnSeS/ZnS NCs and blue-emitting CdZnS/ZnS NCs in polar solvents are 97%, 80% and 72%, respectively. Further study reveals that the passivated Lewis basic sites of ILANs by metal cations boost the efficiency of radiative recombination of electron-hole pairs. While the passivation of Lewis basic sites leads to a high PLQY of ILANs, the exposed Lewis acidic sites provide the possibility for in situ tuning of the functions of NCs, creating opportunities for direct optical patterning of functional NCs with high resolution.

The all-inorganic nature of CsPbI3 perovskites allows to enhance stability in perovskite devices. Research efforts have led to improved stability of the black phase in CsPbI3 films; however, these strategies-including strain and doping-are based on organic-ligand-capped perovskites, which prevent perovskites from forming the close-packed quantum dot (QD) solids necessary to achieve high charge and thermal transport. We developed an inorganic ligand exchange that leads to CsPbI3 QD films with superior phase stability and increased thermal transport. The atomic-ligand-exchanged QD films, once mechanically coupled, exhibit improved phase stability, and we link this to distributing strain across the film. Operando measurements of the temperature of the LEDs indicate that KI-exchanged QD films exhibit increased thermal transport compared to controls that rely on organic ligands. The LEDs exhibit a maximum EQE of 23 % with an electroluminescence emission centered at 640 nm (FWHM: ≈31 nm). These red LEDs provide an operating half-lifetime of 10 h (luminance of 200 cd m-2 ) and an operating stability that is 6× higher than that of control devices.

We reported the first synthesis of Mn2+ doped Cs3Sb2Clx/Br9-x (0 ≤ x ≤ 9) perovskite quantum dots (PQDs) by regulating the coprecipitation of Mn2+ and Sb3+ with thiol ligands. These lead-free PQDs demonstrated bright photoluminescence emission centered at 660 nm and a high quantum yield of ∼49%, making them suitable for optical applications.

Precise, sensitive, and reversible thermochromic luminescent sensing can be achieved by PEAMnBrxI3−x (x = 0/1/2/3). Their luminescence ratios of green to red exhibited a reversible linear response to the temperature increment process (from 40 °C to 120 °C), bright luminescence under high temperature, and reversible heating–cooling circulation performance. Based on the thermochromic luminescence properties, the PEAMnBr2I–polymer film was used for precise and real-time temperature sensing. A deep understanding of their thermochromic luminescence mechanism can facilitate the design of thermochromic materials with high performance and their wider applications.

The strategy of constructing the core/shell structure is of great importance in emitting semiconductor nanocrystals. However, the coating on soft metal halide perovskite nanocrystals at the single particle level remains a challenge because of the low compatibility between perovskites and common wide-band-gap semiconductors, such as ZnS and CdS. In addition, using these semiconductors as the shell layer requires high reaction temperatures, which often lead to undesirable chemical transformation. Herein we report a general route to passivate the perovskite nanocrystals by insulating metal sulfate shells. The passivating shell is created around the as-synthesized CsPbBr3 perovskite nanocrystals by initiating the reaction between an organic ammonium sulfate and a variety of metal ions in the presence of ligands. This new method allowed for creating insulating metal sulfate shells with controllable thicknesses and without unwanted chemical transformation. Importantly, these novel core/shell-structured nanocrystals show photoluminescence quantum yields near unity, highly suppressed energy transfer in film and suppressed halide exchange in solution.

In recent years, two-dimensional (2D) layered tin halide perovskites have attracted much attention due to their excellent luminescence properties compared with their three-dimensional (3D) analogs. Here, we synthesized 2D perovskites of the form (RNH3)2SnBr4 through a facile hot-injection approach without the use of toxic tri-n-octylphosphine (TOP) as the solvent. We found that these compounds have strong photoluminescence (PL) emission with high PL quantum yields (QY) of 35% ((C6H13NH3)2SnBr4), 82% ((C8H17NH3)2SnBr4), 60% ((C12H25NH3)2SnBr4) and 50% ((C18H35NH3)2SnBr4). Among them, ((C6H13NH3)2SnBr4) was synthesized for the first time; however, (C18H36NH3)2SnBr4 perovskites showed the best stability with a PL QY decrease of less than 1% after 30 days under ambient air and humidity conditions. In addition, other 2D (C8H17NH3)2SnX4 (X = Br, I, or mixture) perovskites were prepared by adjusting the halide ratio, resulting in spectral tunability from yellow to red. Interestingly, through Zn2+ doping, the morphology became more uniform, and the PL stability was significantly improved. Finally, we used Zn2+-doped (C8H17NH3)2SnBr4 yellow phosphor to fabricate UV-pumped yellow LEDs. We expect these 2D perovskites to be promising phosphors in future solid-state lighting and display technologies.

Recently, two-dimensional (2D) metal halide perovskite materials with wide application in perovskite-based solar cells have attracted significant attention. Among them, 2D mixed lead–tin perovskites have not been systematically explored. Herein, we synthesize a 2D phenethylammonium (PEA) tin–lead bromide perovskite, PEA2SnxPb1−xBr4, via a simple solution-phase approach without toxic reagents and high temperatures. By tuning the ratio of Sn and Pb, the UV-vis absorption spectra showed unique bandgap bending behaviors. DFT calculations indicate the key effects of spin–orbital coupling (SOC) without the interference of lattice distortion. Moreover, we provided the standard equation with a correction term to introduce the influence of SOC. These results not only provide a step forward towards the bandgap engineering of perovskites, but also help to expand the application of 2D perovskite materials.

A novel triphenylphosphine (TPP) treatment strategy was developed to prepare the near-infrared emission CsPbI3 nanocrystal (NC)-polymer composite thin-film luminescent solar concentrators (LSCs) featuring high absolute photoluminescence quantum yield (PLQY), low reabsorption, and high stability. The PL emission of the LSCs is centered at about 700 nm with 99.4±0.4 % PLQY and narrow full width at half maximum (FWHM) of 75 meV (30 nm). Compared with LSCs prepared with classic CsPbI3 NCs, the stability of the LSCs after TPP treatments has been greatly improved, even after long-term (30 days) immersion in water and strong mercury-lamp irradiation (50 mW cm-2 ). Owing to the presence of lone-pair electrons on the phosphorus atom, TPP is also used as a photoinitiator, with higher efficiency than other common photoinitiators. Large-area (ca. 75 cm2 ) infrared LSCs were achieved with a high optical conversion efficiency of 3.1 % at a geometric factor of 10.

Perovskite-based light-emitting diodes (PeLEDs) are arousing great interest as promising technology for next-generation displays due to their narrow emission linewidth, tunable emission wavelength, and high photoluminescence quantum yield. Due to the superiorities of the simple fabricating process and high efficiency, the in situ preparation of PeLEDs has attracted more attention. However, numerous defects are induced due to the ligand loss in the in situ fabrication of the perovskite film, which restricts the performance improvement of PeLEDs to a larger extent. Here, we introduce a dual ligand 2,2-diphenylethylamine bromide (DPEA-Br) in precursor solution and n-octylphosphonic acid (OPA) in antisolvent for in situ fabricating FAPbBr3 perovskite nanocrystals (PNCs). As a result, the OPA–FAPbBr3 PNC films demonstrate a higher crystallinity, a longer radiative lifetime, and an improved environmental stability, due to the synergistic effect of compensating ligands and passivating defects of OPA. Finally, we obtain a significantly enhanced device efficiency of a maximum luminance of 3273 cd m−2 and a current efficiency of 17.7 cd A−1, which are 12.5 times and 6.1 times higher than those of the control device, respectively. The ligand compensation method with OPA proposed in this work can provide a robust platform for achieving high-quality PNC films and highly efficient PeLEDs.

Manganese-doped perovskite nanocrystals (NCs) have been synthesized by a novel two-step hot-injection strategy with an unprecedented Mn doping efficiency of 48.5%, bright orange emission under ultraviolet light and X-ray excitation and a photoluminescence quantum yield of 84.4%, making them excellent luminescent materials.

Since the layer erosion often happens during the solution-processable optoelectronic devices, and thus the efficiency of inkjet-printed quantum dot light emitting diodes (QLEDs) lags behind those of spin-coated counterparts severely. Indeed, the pursuit of high-performance inkjet-printed QLEDs is fundamentally challenging. Herein, a binary QDs ink based on cyclohexylbenzene (CHB) and indane was developed with red CdZnSe/ZnS core/shell structure without using any other additives for inkjet printing. Three common hole transport materials (HTMs), poly (9-vinlycarbazole) (PVK), poly[(9,9'-dioctylfluorenyl-2,7- diyl)-co-(4,4'-(N-(4-sec-butyl))diphenylamine)] (TFB) and poly (N, N′-bis (4-butylphenyl-N, N′-bis (phenyl) benzidine) (Poly-TPD), were invoked as the underlying layer to print QDs emissive layer, and their surface wettability and solvent resistance were systematically investigated. Among them, PVK exhibited excellent surface wettability and solvent resistance, accordingly, the PVK-based printed red QLEDs exhibited the current efficiency of 28.8 cd A−1 and the maximum external quantum efficiency (EQE) over 17.0%, which was comparable to the spin-coated QLEDs (19.8%). These results demonstrate the fabrication of efficient inkjet-printed QLED devices, which will be meaningful for printed QLEDs displays.

Cesium lead halide perovskites have been arise as a new promising materials for optoelectronic applications. On this basis, zero-dimensional inorganic perovskites, Cs4PbBr6 can be an important candidate because of the excellent stability. However, obtaining the high photoluminescence quantum yield (PLQY) of phase-pure Cs4PbBr6 Perovskites still remains a challenge. Here, we synthesized the phase-pure Cs4PbBr6 crystals through a simple ligand-assisted, reprecipitation strategy under room-temperature. We altered the assisted ligands that used in the experiment synthesis, such as substitute dodecylamine for oleylamine, and obtained high near PLQY (95.1%) of phase-pure Cs4PbBr6 Perovskites. We revealed the extra oleic acid (OA), such as the ratio of OA and dodecylamine for 10 : 1 , would improve their PLQY. Most importantly, we demonstrated the short lifetime decay is caused by the recombination of trapped exciton inside the crystal but the long lifetime decay is attributed to the recombination of the surface energy states, and provided a great comprehension in photophysical of Cs4PbBr6 Perovskite materials.

Nanocarbon fluorescence materials are promising color converters for multicolor emission via phosphor-coated light emitting devices (LEDs). Herein, a facile time-controlled solvothermal route was developed to prepare solid-state multicolor nanocarbon emitters comprising dot/sheet nanohybrids. The nanocarbons demonstrate an aggregation-induced color switching behavior, leading to tunable light emission from blue to yellow by modulating the solvothermal reaction time. Particularly, these emitters show outstanding film-forming ability directly and a high production yield (∼40%). Moreover, the nanocarbon-coated ultraviolet LEDs exhibit high quality multicolor light emission and excellent color stability at high voltages, impelling the development of emerging carbon phosphors in fundamental research studies and practical applications.

The high-performance light-management slabs made of low-cost, highly emissive, and ultra-stable nanocrystal (NC)-polymer composites are desirable for application in large-area luminescent solar concentrators (LSCs). However, although the reported photoluminescence (PL) quantum yield (QY) of NCs in solution is up to 90%, PL QY of NCs in a polymer matrix is usually low, which limits the performance of LSCs. Herein, we demonstrated a new strategy for the synthesis of formamidinium lead bromide (FAPbBr3) NCs via room-temperature solvent-induced reprecipitation using dicarboxylic acids as ligands and the preparation of NC-polymer composite slabs for LSCs. Due to the strong binding of dicarboxylic acids, the as-synthesized decanedioic acid (DA)-capped FAPbBr3 NCs displayed high PL QY (90 ± 5%), increased chemical yield, and improved stability as compared to monocarboxylic oleic acid (OA)-capped NCs (PL QY of 80 ± 5%) synthesized in the same conditions. Furthermore, in the presence of toluene as the solvent, these DA-capped NCs exhibited good compatibility with polystyrene (PS); thus, the NCs-PS slurry exhibited appropriate viscosity. Therefore, it was convenient to deposit the slurry onto commercially available polymethyl methacrylate (PMMA) slabs with a standard doctor blade. The optimized NCs-PS-PMMA slabs with PL QY of 92 ± 5% were sustained for over 1000 hours under high-temperature (60 °C) and high-humidity (relative humidity, RH = 90%) environments. The results show that the perovskite NC-based slabs developed in this study have the advantages of low cost, high emissivity, and good stability and may contribute to the field of LSCs.

Recently, lead halide perovskites with outstanding emission performance have become new candidate materials for light-emitting devices and displays; however, the toxicity of lead and instability of halide perovskites remain significant challenges. Herein, we report the aqueous acid-based synthesis of highly emissive two-dimensional (2D) tin halide perovskites, (octylammonium)2SnX4 (X = Br, I, or mixtures thereof), which displayed a high absolute photoluminescence (PL) quantum yield of near-unity in the solid-state, PL emission centered at 600 nm with a broad bandwidth (136 nm), a large Stokes shift (250 nm), long-lived luminescence (τ = 3.3 μs), and zero overlap between their absorption and emission spectra. Significantly, the stability study of 2D tin halide perovskites monitored by the PL quantum yield showed no changes after 240 days of storage at room temperature under ambient air and humidity conditions. The PL emission of the 2D tin halide perovskites was tuned from yellow to deep red by controlling halide composition. Furthermore, new yellow phosphors with superior optical properties are used to fabricate UV pumped white light emitting diodes (WLEDs). We expect these results to facilitate the development of new environmentally friendly and high-performance phosphors for future lighting and display technologies.

Although the power conversion efficiency of perovskite solar cells has exceeded 23%, the poor ambient stability of organic–inorganic halide perovskites poses a challenge for their commercialization. Comprehensive understanding of the underlying degradation mechanisms is a crucial step to seek approaches that can effectively suppress the degradation of perovskites. Herein, on the basis of extensive first-principles calculations, a three-step photo-oxidative degradation mechanism of MAPbI3 at the atomic level is revealed. We find that, in a dry ambient environment, the photo-generated superoxide anions (O2−) first lead to fast surface oxidation. However, further oxidation of the perovskite interior is hindered by the solid oxidation product. The fresh water produced in surface oxidation leads to the hydration of the inner perovskite and eventual breakage of the MAPbI3 lattice. We devise a practical strategy for protecting MAPbI3 from photo-induced decomposition by anchoring hydrophobic 2-(4-fluorophenyl)propan-2-amine on the surface of MAPbI3. The surface modification significantly retards the photo-induced decomposition.

Emissive cross-linkers are of special interest for polymer science because of their ability to endow polymer networks with luminescent properties. Methylammonium lead halide perovskite nanoparticles (MAPbCl xBr3- x NPs) are extensively explored for optical and optoelectronic applications. In this work, MAPbCl xBr3- x NPs with cross-linkable and polymerizable ligands are successfully prepared as new emissive cross-linkers for polymer networks. Commercially available reagent 2-aminoethyl methacrylate hydrochloride (AMHCl) can act as a ligand to stabilize MAPbBr3 NPs in solution. Compared with traditional ligands (oleic acid and oleylamine), AMHCl retains the architecture of perovskite effectively and affords polymerizable groups (vinyl) on the surface of perovskites. The as-prepared MAPbCl xBr3- x NPs can serve as cross-linkers in the radical polymerization of (meth)acrylates by UV-light to form polymer networks. Meanwhile, such cross-linkable emitters exhibit bright luminescence and color-tunability at room temperature, attributed by a unique halide exchange of perovskites between CH3NH3Br and AMHCl, which provides the polymer networks with varied emissive bands. These perovskite-crosslinked networks showed high air stability, water stability, and prominent photoluminescence quantum yields. On the basis of these excellent properties, white-light-emitting diodes were successfully fabricated from these perovskite-crosslinked composites with color-coordinate values at (0.316, 0.315), very close to the standard coordinates of white light. This work elucidates a new and convenient technique to convert nanocrystals into luminescent cross-linkers to build functional polymeric networks for technological applications.

Recently, the pursuit of high photoluminescence quantum yields (PLQYs) for blue emission in perovskite nanocrystals (NCs) has attracted increased attention because the QY of blue NCs lags behind those of green and red ones severely, which is fatal for three-primary-color displays. Here, we propose an in situ PbBr64– octahedra passivation strategy to achieve a 96% absolute QY for the ultrapure (line width = 12 nm) blue emission from CsPbBr3 nanoplatelets (NPLs), and both values rank first among perovskite NCs with blue emission. From the aspect of constructing intact PbBr64– octahedra, additional Br– was introduced to drive the ionic equilibrium to form intact Pb–Br octahedra. The reduced Br vacancy and inhibited nonradiative recombination processes are well proved by reduced Urbach energy, increased Pb–Br bonds, and slower transient absorption delay. Blue light-emitting diodes (LEDs) using NPLs were fabricated, and a high external quantum efficiency (EQE) of 0.124% with an emission line width of ∼12 nm wa...

This communication describes a facile hot-injection method for the synthesis of novel micrometer-size formamidinium lead bromide perovskite (FAPbBr3) nanosheets of monolayer thickness (around 2.4 nm). Due to the strong quantum confinement effect, the as-synthesized large-sized perovskite nanosheets displayed an unprecedented extremely blue-shifted first sharp excitonic absorption peak at 435 nm and an emission peak at 437 nm, as compared to that of bulk FAPbBr3 crystals at 551 nm.

Compositionally related cesium lead halide materials, such as CsPb2X5, have attracted great interest due to their considerable optoelectronic/optical properties as well as improved stability. Currently, CsPb2Br5 nanocrystals can be well-designed by tuning the ligands or precursor ratio, whereas, CsPb2X5 (with Cl− or I−) nanocrystals can only be obtained by the anion exchange method. Herein, we report a method to directly synthesize CsPb2X5 facilitated by thiol ligands. The morphology of CsPb2X5 can be designed as a nanowire. Importantly, the stability of directly synthesized CsPb2X5 nanowires is much improved when compared with the stabilities of the materials obtained by the anion-exchange method. We believe that this method will promote the application of 1D tetragonal CsPb2X5 in optoelectronics, optics and other fields.

Controlled synthesis of colloidal all-inorganic lead halide perovskite semiconductor nanocrystals, such as CsPbBr3, with tunable size, shape, composition, and crystalline phase have recently attracted wide interest for photonic and optoelectronic applications. Herein, we report a new strategy for using alkyl-thiols to induce the transformation of CsPbBr3 to perovskite-related cesium lead halide (CsPb2Br5) with controlled morphology and a crystalline phase at room temperature. By rational tuning the ratios of the alkyl-thiol ligands to alkyl-amines or to alkyl-acids, the as-synthesized colloidal nanocrystals can be rationally controlled from orthorhombic crystalline-phase CsPbBr3 to tetragonal-phase CsPb2Br5 nanosheets and nanowires with high yield. Significantly, the tetragonal CsPb2Br5 nanowires and nanosheets have high stability in high-temperature and high-humidity environments. These findings may open new directions for large-scale synthesis of shape- and crystalline phase-controlled perovskite nanocr...

Hollow nanocrystals have attracted considerable attention in many areas of materials science because of their unique geometry, large surface area, high loading capacity and low density, and potential applications in catalysis, energy storage, drug delivery, and molecular separation. So far, numerous hollow nanostructured materials, such as noble metals, metallic oxides, hydroxides, and chalcogenides, have been reported. However, there is no report about the hollow metal halide perovskite nanocrystals yet. Herein, for the first time, we report the controlled synthesis of metal halide perovskite hollow nanocrystals, i.e., CsSnBr3 cubic nanocages, through a facile hot-injection colloidal approach. The formation of nanocages was controlled by rationally choosing the precursors and reaction temperature and was achieved through the self-assembly driven process. The as-synthesized CsSnBr3 nanocages exhibit excellent oxygen resistibility under desiccation conditions. Furthermore, treatment of CsSnBr3 nanocages wi...

Lead halide perovskites with well-defined morphology have attracted attention for their unique properties as a promising new class of semiconductor materials in photovoltaics and optoelectronics. However, controlling morphologies and compositions of perovskite nanostructures with improved stability, especially for double cation lead halide perovskite, still remains a challenge. Here, we demonstrate a colloidal synthetic approach for direct synthesis of stable single-crystal formamidinium (FA) cesium double cation lead halide FA0.33Cs0.67PbBr3–xIx (0 ≤ x ≤ 3) perovskite nanostructures with controllable morphology over a wide range of halide compositions, without using a previous anion-exchange process. The presence of FA alloyed in the A site for the pure cesium lead halide perovskite structure can stabilize the nanocrystals while delivering a better balance between structure and composition. On the basis of the FA0.33Cs0.67PbBr3–xIx alloy perovskite system, we achieved nanowires and nanosheets with high y...